The invention relates to a measuring transformer for completely insulated, metal-clad, high-voltage installations. The transformer includes a tube member arranged inside the metal outer tube of the high-voltage installation. The tube member forms a surface-type electrode and conjointly defines with the high-voltage conductor of the installation a high-potential capacitor of a capacitive voltage divider which includes a low-potential capacitor connected to the high-potential capacitor.
A measuring transformer of this type is described in U.S. Pat. No. 3,763,378. The measuring transformer of this reference can be configured as a combined current and voltage transformer by forming the surface-type electrode by a conductive layer applied to the inner surface of a current transformer casing which is arranged inside the outer tube of the high-voltage installation. The casing houses at least one current transformer core with a secondary coil system mounted thereon.